Riboflavin lowers homocysteine in individuals homozygous for the MTHFR 677C->T polymorphism

McNulty H, Dowey le RC, Strain JJ, Dunne A, Ward M, Molloy AM, et al.

Published in Circulation, Vol. 113 (1), pp. 74-80

Methodology

Randomised, placebo-controlled trial in healthy adults aged 18-65 selected from a register of 680 by MTHFR C677T genotype: 35 TT, 26 CT and 28 CC. Participants were randomised within each genotype group to 1.6 mg/day riboflavin or placebo for 12 weeks; plasma homocysteine was the outcome.

Key Findings

Riboflavin improved riboflavin status equally in all genotypes, but homocysteine fell only in the TT group: by 22% overall (16.1 to 12.5 umol/L, P = 0.003) and by 40% in TT participants with lower riboflavin status at baseline. CC and CT groups showed no homocysteine response.

Conclusions

Homocysteine is highly responsive to riboflavin specifically in people with the MTHFR 677TT genotype.

Limitations

Small genotype groups; 12 weeks; homocysteine is a biomarker, not a clinical outcome; from the Ulster group that ran most of the later riboflavin trials.